Synthesis of a novel tricyclic 4-quinolone. Incorporation of a spiro-cyclopropyl group at N1 by bridging to C2

An important pharmacophore in many quinolone antiinfectives is the N1 cyclopropane. By incorporating the cyclopropane into a N1 to C2 bridge, the first quinolone substrate incorporating a spiro fused cyclopropane, 8,9,10-trifluoro-2,3,4,6-tetrahydro-6-oxospiro[1H-benzo[c]quinolizine-1,l-cyclopropane]-5-carboxylic acid, ethyl ester ( 8 ), was prepared.     

The autoreduction of pertechnetate in aqueous,alkaline solutions

Summary The autoreduction of pertechnetate (⁹⁹TcO₄^-) to Tc(IV/V) alkoxide complexes in aqueous, alkaline, solutions is described. Solutions of sodium pertechnetate (0.01M) reacted with nitrogen and oxygen donor ligands (1.0M) in 2M sodium hydroxide. Solutions containing nitrogen donor ligands (e.g., EDTA) showed the initial formation of lightly colored complexes followed by rapid decomposition in air. In contrast, stable, reduced complexes were formed within minutes of mixing pertechnetate with mono- and disaccharides in strong base, as indicated by a persistent color change. Chemical yields of these reactions were determined by thin layer chromatography or paper chromatography and radiochemically assayed with a Bioscan imaging scanner. Analysis by UV-vis spectroscopy suggested that Tc(IV) or Tc(V) complexes were produced, with the oxidation state dependent on the reducing ligand. These experiments may help explain the reduction of pertechnetate to the soluble complexes that have been found in the Hanford nuclear waste tanks.     

Beiträge zur Kenntnis der Gelatinegerbung

Ohne Zusammenfassung     

The productive scientific career of Charles Pedersen (October 3, 1904–October 26, 1989)

Charles Pedersen's career is reviewed from the time of his early life in Korea and Japan and scientific training in the United States to the present. His 42-year research career was practically and scientifically productive, leading finally to a share of the Nobel prize in chemistry for 1987. Commercially significant accomplishments included a large improvement in the yield of tetraethylead antiknock and discovery of the first oil soluble agents for inhibiting catalytic effects of copper in degradation of petroleum products and rubber. This led to a study of the interactions of metals with chelating agents and the resultant effects on oxidation reactions, thence to the behavior of peroxides and their reactions with substrates. He also discovered the antiknock activity of ferrocene. While studying the effects of ligands on the catalytic behavior of vanadium he discovered the crown compounds and their ability to include alkali metal ions. He devoted the last years of his career to elaborating their chemistry.Taken in part with permission fromCurrent Topics in Macrocyclic Chemistry in Japan, E. Kimura (ed.), Hiroshima University School of Medicine, Hiroshima, 1987.     

Zur Bestimmung des Gerbstoffs

Ohne Zusammenfassung     

Ge2Co6(CO)20: Ein Ge‐Co‐Cluster ausgehend von gelöstem GeBr

Ge₂Co₆(CO)₂₀: A Ge‐Co Cluster Compound from Solubilized GeBr The Ge‐Co cluster Ge₂Co₆(CO)₂₀ is synthesized from a reaction of a GeBr solution with Co₂(CO)₈. Isolation of suitable crystals allows the determination of the crystal structure of Ge₂Co₆(CO)₂₀, being the lacking member in the row GeCo₄(CO)₁₄ – Ge₂Co₆(CO)₂₀ – Ge₃Co₈(CO)₂₆.     

Simultaneous saccharification and cofermentation of peracetic acid-pretreated biomass

Previous work in our laboratories has demonstrated the effectiveness of peracetic acid for improving enzymatic digestibility of lignocellulosic materials. The use of dilute alkali solutions as a pre-pretreatment prior to peracetic acid lignin oxidation increased carbohydrate hydrolysis yields in a synergistic as opposed to additive manner. Deacetylation of xylan is easily achieved using dilute alkali solutions under mild conditions. In this article, we evaluate the effectiveness of peracetic acid combined with an alkaline pre-pretreatment through simulataneous saccharification and cofermentation (SSCF) of pretreated hybrid poplar wood and sugar can ebagasse. Respective ethanol yields of 92.8 and 91.9% of theoretical are achieved using 6% NaOH/15% peracetic acid-pretreated substrates and recombinant Zymomonas mobilis CP4/p ZB5. Reduction of acetyl groups of the lignocellulosic materials is demonstrated following alkaline pre-pretreatments. Such processing may be helpful in reducing peracetic acid requirements. The influence of deacetylation is more significant in combined pretreatments using lower peracetic acid loadings.